From 4503d03aa3aa5b5f35f3db4cf1de838273e051a7 Mon Sep 17 00:00:00 2001

From: tbordaz <tbordaz@redhat.com>

Date: Thu, 23 Sep 2021 10:48:50 +0200

Subject: [PATCH 1/2] Issue 4925 - Performance ACI: targetfilter evaluation

 result can be reused (#4926)

Bug description:

	An ACI may contain targetfilter. For a given returned entry, of a

        SRCH request, the same targetfilter is evaluated for each of the

        returned attributes.

        Once the filter has been evaluated, it is useless to reevaluate

        it for a next attribute.

Fix description:

	The fix implements a very simple cache (linked list) that keeps

        the results of the previously evaluated 'targetfilter'.

        This cache is per-entry. For an operation, a aclpb is allocated

        that is used to evaluate ACIs against each successive entry.

        Each time a candidate entry is added in the aclpb

        (acl_access_allowed), the cache (aclpb_curr_entry_targetfilters)

        is freed. Then for each 'targetfilter', the original targetfilter

        is lookup from the cache. If this is the first evaluation of it

        then the result of the evaluation is stored into the cache using

        the original targetfilter as the key in the cache

	The key to lookup/store the cache is the string representation

        of the targetfilter. The string contains a redzone to detect

        that the filter exceeds the maximum size (2K). If it exceeds

        then the key is invalid and the lookup/store is noop.

relates: #4925

Reviewed by: Mark Reynolds, William Brown (Thanks)

Platforms tested: F34

---

 ldap/servers/plugins/acl/acl.c     | 138 +++++++++++++++++++++++++++--

 ldap/servers/plugins/acl/acl.h     |  14 +++

 ldap/servers/plugins/acl/acl_ext.c |  12 +++

 ldap/servers/slapd/libglobs.c      |  29 ++++++

 ldap/servers/slapd/proto-slap.h    |   2 +

 ldap/servers/slapd/slap.h          |   2 +

 6 files changed, 191 insertions(+), 6 deletions(-)

diff --git a/ldap/servers/plugins/acl/acl.c b/ldap/servers/plugins/acl/acl.c

index ecd23aa88..646a369db 100644

--- a/ldap/servers/plugins/acl/acl.c

+++ b/ldap/servers/plugins/acl/acl.c

@@ -66,6 +66,9 @@ static void print_access_control_summary(char *source,

                                          const char *edn,

                                          aclResultReason_t *acl_reason);

 static int check_rdn_access(Slapi_PBlock *pb, Slapi_Entry *e, const char *newrdn, int access);

+static struct targetfilter_cached_result *targetfilter_cache_lookup(struct acl_pblock *aclpb, char *filter, PRBool filter_valid);

+static void targetfilter_cache_add(struct acl_pblock *aclpb, char *filter, int result, PRBool filter_valid);

+

 /*

@@ -175,6 +178,70 @@ check_rdn_access(Slapi_PBlock *pb, Slapi_Entry *e, const char *dn, int access)

     return (retCode);

 }

+/* Retrieves, in the targetfilter cache (list), this

+ * filter in case it was already evaluated

+ *

+ * filter: key to retrieve the evaluation in the cache

+ * filter_valid: PR_FALSE means that the filter key is truncated, PR_TRUE else

+ */

+static struct targetfilter_cached_result *

+targetfilter_cache_lookup(struct acl_pblock *aclpb, char *filter, PRBool filter_valid)

+{

+    struct targetfilter_cached_result *results;

+    if (! aclpb->targetfilter_cache_enabled) {

+        /* targetfilter cache is disabled */

+        return NULL;

+    }

+    if (filter == NULL) {

+        return NULL;

+    }

+    for(results = aclpb->aclpb_curr_entry_targetfilters; results; results = results->next) {

+        if (strcmp(results->filter, filter) == 0) {

+            return results;

+        }

+    }

+

+    return NULL;

+}

+

+/* Free all evaluations cached for this current entry */

+void

+targetfilter_cache_free(struct acl_pblock *aclpb)

+{

+    struct targetfilter_cached_result *results, *next;

+    if (aclpb == NULL) {

+        return;

+    }

+    for(results = aclpb->aclpb_curr_entry_targetfilters; results;) {

+        next = results->next;

+        slapi_ch_free_string(&results->filter);

+        slapi_ch_free((void **) &results);

+        results = next;

+    }

+    aclpb->aclpb_curr_entry_targetfilters = NULL;

+}

+

+/* add a new targetfilter evaluation into the cache (per entry)

+ * ATM just use a linked list of evaluation

+ *

+ * filter: key to retrieve the evaluation in the cache

+ * result: result of the evaluation

+ * filter_valid: PR_FALSE means that the filter key is truncated, PR_TRUE else

+ */

+static void

+targetfilter_cache_add(struct acl_pblock *aclpb, char *filter, int result, PRBool filter_valid)

+{

+    struct targetfilter_cached_result *results;

+    if (! filter_valid || ! aclpb->targetfilter_cache_enabled) {

+        /* targetfilter cache is disabled or filter is truncated */

+        return;

+    }

+    results = (struct targetfilter_cached_result *) slapi_ch_calloc(1, (sizeof(struct targetfilter_cached_result)));

+    results->filter = slapi_ch_strdup(filter);

+    results->next = aclpb->aclpb_curr_entry_targetfilters;

+    results->matching_result = result;

+    aclpb->aclpb_curr_entry_targetfilters = results;

+}

 /***************************************************************************

 *

 * acl_access_allowed

@@ -495,6 +562,7 @@ acl_access_allowed(

         /* Keep the ptr to the current entry */

         aclpb->aclpb_curr_entry = (Slapi_Entry *)e;

+        targetfilter_cache_free(aclpb);

         /* Get the attr info */

         deallocate_attrEval = acl__get_attrEval(aclpb, attr);

@@ -1922,7 +1990,7 @@ acl_modified(Slapi_PBlock *pb, int optype, Slapi_DN *e_sdn, void *change)

 *    None.

 *

 **************************************************************************/

-static int

+int

 acl__scan_for_acis(Acl_PBlock *aclpb, int *err)

 {

     aci_t *aci;

@@ -2403,10 +2471,68 @@ acl__resource_match_aci(Acl_PBlock *aclpb, aci_t *aci, int skip_attrEval, int *a

                                                     ACL_EVAL_TARGET_FILTER);

             slapi_ch_free((void **)&lasinfo);

         } else {

-            if (slapi_vattr_filter_test(NULL, aclpb->aclpb_curr_entry,

-                                        aci->targetFilter,

-                                        0 /*don't do access check*/) != 0) {

-                filter_matched = ACL_FALSE;

+            Slapi_DN *sdn;

+            char* attr_evaluated = "None";

+            char logbuf[2048] = {0};

+            char *redzone = "the redzone";

+            int32_t redzone_idx;

+            char *filterstr; /* key to retrieve/add targetfilter value in the cache */

+            PRBool valid_filter;

+            struct targetfilter_cached_result *previous_filter_test;

+

+            /* only usefull for debug purpose */

+            if (aclpb->aclpb_curr_attrEval && aclpb->aclpb_curr_attrEval->attrEval_name) {

+                attr_evaluated = aclpb->aclpb_curr_attrEval->attrEval_name;

+            }

+            sdn = slapi_entry_get_sdn(aclpb->aclpb_curr_entry);

+

+            /* The key for the cache is the string representation of the original filter

+             * If the string can not fit into the provided buffer (overwrite redzone)

+             * then the filter is said invalid (for the cache) and it will be evaluated

+             */

+            redzone_idx = sizeof(logbuf) - 1 - strlen(redzone);

+            strcpy(&logbuf[redzone_idx], redzone);

+            filterstr = slapi_filter_to_string(aci->targetFilter, logbuf, sizeof(logbuf));

+

+            /* if the redzone was overwritten that means filterstr is truncated and not valid */

+            valid_filter = (strcmp(&logbuf[redzone_idx], redzone) == 0);

+            if (!valid_filter) {

+                strcpy(&logbuf[50], "...");

+                slapi_log_err(SLAPI_LOG_ACL, "acl__ressource_match_aci", "targetfilter too large (can not be cache) %s\n", logbuf);

+            }

+

+            previous_filter_test = targetfilter_cache_lookup(aclpb, filterstr, valid_filter);

+            if (previous_filter_test) {

+                /* The filter was already evaluated against that same entry */

+                if (previous_filter_test->matching_result == 0) {

+                    slapi_log_err(SLAPI_LOG_ACL, "acl__ressource_match_aci", "cached result for entry %s did NOT match %s (%s)\n",

+                            slapi_sdn_get_ndn(sdn),

+                            filterstr,

+                            attr_evaluated);

+                    filter_matched = ACL_FALSE;

+                } else {

+                    slapi_log_err(SLAPI_LOG_ACL, "acl__ressource_match_aci", "cached result for entry %s did match %s (%s)\n",

+                            slapi_sdn_get_ndn(sdn),

+                            filterstr,

+                            attr_evaluated);

+                }

+            } else {

+                /* The filter has not already been evaluated against that entry

+                 * evaluate it and cache the result

+                 */

+                if (slapi_vattr_filter_test(NULL, aclpb->aclpb_curr_entry,

+                        aci->targetFilter,

+                        0 /*don't do access check*/) != 0) {

+                    filter_matched = ACL_FALSE;

+                    targetfilter_cache_add(aclpb, filterstr, 0, valid_filter); /* does not match */

+                } else {

+                    targetfilter_cache_add(aclpb, filterstr, 1, valid_filter); /* does match */

+                }

+                slapi_log_err(SLAPI_LOG_ACL, "acl__ressource_match_aci", "entry %s %s match %s (%s)\n",

+                        slapi_sdn_get_ndn(sdn),

+                        filter_matched == ACL_FALSE ? "does not" : "does",

+                        filterstr,

+                        attr_evaluated);

             }

         }

@@ -2862,7 +2988,7 @@ acl__resource_match_aci_EXIT:

 *    None.

 *

 **************************************************************************/

-static int

+int

 acl__TestRights(Acl_PBlock *aclpb, int access, const char **right, const char **map_generic, aclResultReason_t *result_reason)

 {

     ACLEvalHandle_t *acleval;

diff --git a/ldap/servers/plugins/acl/acl.h b/ldap/servers/plugins/acl/acl.h

index 5d453d825..cf74510e7 100644

--- a/ldap/servers/plugins/acl/acl.h

+++ b/ldap/servers/plugins/acl/acl.h

@@ -407,6 +407,17 @@ struct aci_container

 };

 typedef struct aci_container AciContainer;

+/* This structure is stored in the aclpb.

+ * It is a linked list containing the result of

+ * the filter matching against a specific entry.

+ *

+ * This list is free for each new entry in the aclpb*/

+struct targetfilter_cached_result {

+    char *filter;                            /* strdup of string representation of aci->targetFilter */

+    int matching_result;                     /* 0 does not match / 1 does match */

+    struct targetfilter_cached_result *next; /* next targetfilter already evaluated */

+};

+

 struct acl_pblock

 {

     int aclpb_state;

@@ -476,6 +487,8 @@ struct acl_pblock

     /* Current entry/dn/attr evaluation info */

     Slapi_Entry *aclpb_curr_entry; /* current Entry being processed */

+    int32_t targetfilter_cache_enabled;

+    struct targetfilter_cached_result *aclpb_curr_entry_targetfilters;

     int aclpb_num_entries;

     Slapi_DN *aclpb_curr_entry_sdn;    /* Entry's SDN */

     Slapi_DN *aclpb_authorization_sdn; /* dn used for authorization */

@@ -723,6 +736,7 @@ void acl_modified(Slapi_PBlock *pb, int optype, Slapi_DN *e_sdn, void *change);

 int acl_access_allowed_disjoint_resource(Slapi_PBlock *pb, Slapi_Entry *e, char *attr, struct berval *val, int access);

 int acl_access_allowed_main(Slapi_PBlock *pb, Slapi_Entry *e, char **attrs, struct berval *val, int access, int flags, char **errbuf);

+void targetfilter_cache_free(struct acl_pblock *aclpb);

 int acl_access_allowed(Slapi_PBlock *pb, Slapi_Entry *e, char *attr, struct berval *val, int access);

 aclUserGroup *acl_get_usersGroup(struct acl_pblock *aclpb, char *n_dn);

 void acl_print_acllib_err(NSErr_t *errp, char *str);

diff --git a/ldap/servers/plugins/acl/acl_ext.c b/ldap/servers/plugins/acl/acl_ext.c

index 31c61c2f4..73dd6c39d 100644

--- a/ldap/servers/plugins/acl/acl_ext.c

+++ b/ldap/servers/plugins/acl/acl_ext.c

@@ -187,6 +187,11 @@ acl_operation_ext_constructor(void *object __attribute__((unused)), void *parent

         slapi_log_err(SLAPI_LOG_ERR, plugin_name,

                       "acl_operation_ext_constructor - Operation extension allocation Failed\n");

     }

+    /* targetfilter_cache toggle set during aclpb allocation

+     * to avoid accessing configuration during the evaluation

+     * of each aci

+     */

+    aclpb->targetfilter_cache_enabled = config_get_targetfilter_cache();

     TNF_PROBE_0_DEBUG(acl_operation_ext_constructor_end, "ACL", "");

@@ -711,6 +716,7 @@ acl__free_aclpb(Acl_PBlock **aclpb_ptr)

     slapi_ch_free((void **)&(aclpb->aclpb_curr_entryEval_context.acle_handles_matched_target));

     slapi_ch_free((void **)&(aclpb->aclpb_prev_entryEval_context.acle_handles_matched_target));

     slapi_ch_free((void **)&(aclpb->aclpb_prev_opEval_context.acle_handles_matched_target));

+    targetfilter_cache_free(aclpb);

     slapi_sdn_free(&aclpb->aclpb_authorization_sdn);

     slapi_sdn_free(&aclpb->aclpb_curr_entry_sdn);

     if (aclpb->aclpb_macro_ht) {

@@ -919,6 +925,12 @@ acl__done_aclpb(struct acl_pblock *aclpb)

                       aclpb->aclpb_acleval ? (char *)aclpb->aclpb_acleval : "NULL");

     }

+    /* This aclpb return to the aclpb pool, make sure

+     * the cached evaluations are freed and that

+     * aclpb_curr_entry_targetfilters is NULL

+     */

+    targetfilter_cache_free(aclpb);

+

     /* Now Free the contents or clean it */

     slapi_sdn_done(aclpb->aclpb_curr_entry_sdn);

     if (aclpb->aclpb_Evalattr)

diff --git a/ldap/servers/slapd/libglobs.c b/ldap/servers/slapd/libglobs.c

index 91c3a4a89..89f7e5344 100644

--- a/ldap/servers/slapd/libglobs.c

+++ b/ldap/servers/slapd/libglobs.c

@@ -211,6 +211,7 @@ slapi_onoff_t init_return_exact_case;

 slapi_onoff_t init_result_tweak;

 slapi_onoff_t init_plugin_track;

 slapi_onoff_t init_moddn_aci;

+slapi_onoff_t init_targetfilter_cache;

 slapi_onoff_t init_lastmod;

 slapi_onoff_t init_readonly;

 slapi_onoff_t init_accesscontrol;

@@ -822,6 +823,11 @@ static struct config_get_and_set

      (void **)&global_slapdFrontendConfig.moddn_aci,

      CONFIG_ON_OFF, (ConfigGetFunc)config_get_moddn_aci,

      &init_moddn_aci},

+    {CONFIG_TARGETFILTER_CACHE_ATTRIBUTE, config_set_targetfilter_cache,

+     NULL, 0,

+     (void **)&global_slapdFrontendConfig.targetfilter_cache,

+     CONFIG_ON_OFF, (ConfigGetFunc)config_get_targetfilter_cache,

+     &init_targetfilter_cache},

     {CONFIG_ATTRIBUTE_NAME_EXCEPTION_ATTRIBUTE, config_set_attrname_exceptions,

      NULL, 0,

      (void **)&global_slapdFrontendConfig.attrname_exceptions,

@@ -1567,6 +1573,7 @@ FrontendConfig_init(void)

     init_syntaxcheck = cfg->syntaxcheck = LDAP_ON;

     init_plugin_track = cfg->plugin_track = LDAP_OFF;

     init_moddn_aci = cfg->moddn_aci = LDAP_ON;

+    init_targetfilter_cache = cfg->targetfilter_cache = LDAP_ON;

     init_syntaxlogging = cfg->syntaxlogging = LDAP_OFF;

     init_dn_validate_strict = cfg->dn_validate_strict = LDAP_OFF;

     init_ds4_compatible_schema = cfg->ds4_compatible_schema = LDAP_OFF;

@@ -3525,6 +3532,21 @@ config_set_moddn_aci(const char *attrname, char *value, char *errorbuf, int appl

     return retVal;

 }

+int32_t

+config_set_targetfilter_cache(const char *attrname, char *value, char *errorbuf, int apply)

+{

+    int32_t retVal = LDAP_SUCCESS;

+    slapdFrontendConfig_t *slapdFrontendConfig = getFrontendConfig();

+

+    retVal = config_set_onoff(attrname,

+                              value,

+                              &(slapdFrontendConfig->targetfilter_cache),

+                              errorbuf,

+                              apply);

+

+    return retVal;

+}

+

 int32_t

 config_set_dynamic_plugins(const char *attrname, char *value, char *errorbuf, int apply)

 {

@@ -5334,6 +5356,13 @@ config_get_moddn_aci(void)

     return slapi_atomic_load_32(&(slapdFrontendConfig->moddn_aci), __ATOMIC_ACQUIRE);

 }

+int32_t

+config_get_targetfilter_cache(void)

+{

+    slapdFrontendConfig_t *slapdFrontendConfig = getFrontendConfig();

+    return slapi_atomic_load_32(&(slapdFrontendConfig->targetfilter_cache), __ATOMIC_ACQUIRE);

+}

+

 int32_t

 config_get_security(void)

 {

diff --git a/ldap/servers/slapd/proto-slap.h b/ldap/servers/slapd/proto-slap.h

index d9fb8fd08..13b41ffa4 100644

--- a/ldap/servers/slapd/proto-slap.h

+++ b/ldap/servers/slapd/proto-slap.h

@@ -262,6 +262,7 @@ int config_set_lastmod(const char *attrname, char *value, char *errorbuf, int ap

 int config_set_nagle(const char *attrname, char *value, char *errorbuf, int apply);

 int config_set_accesscontrol(const char *attrname, char *value, char *errorbuf, int apply);

 int config_set_moddn_aci(const char *attrname, char *value, char *errorbuf, int apply);

+int32_t config_set_targetfilter_cache(const char *attrname, char *value, char *errorbuf, int apply);

 int config_set_security(const char *attrname, char *value, char *errorbuf, int apply);

 int config_set_readonly(const char *attrname, char *value, char *errorbuf, int apply);

 int config_set_schemacheck(const char *attrname, char *value, char *errorbuf, int apply);

@@ -450,6 +451,7 @@ int config_get_accesscontrol(void);

 int config_get_return_exact_case(void);

 int config_get_result_tweak(void);

 int config_get_moddn_aci(void);

+int32_t config_get_targetfilter_cache(void);

 int config_get_security(void);

 int config_get_schemacheck(void);

 int config_get_syntaxcheck(void);

diff --git a/ldap/servers/slapd/slap.h b/ldap/servers/slapd/slap.h

index 007c50b86..b2de66754 100644

--- a/ldap/servers/slapd/slap.h

+++ b/ldap/servers/slapd/slap.h

@@ -2157,6 +2157,7 @@ typedef struct _slapdEntryPoints

 #define CONFIG_REWRITE_RFC1274_ATTRIBUTE "nsslapd-rewrite-rfc1274"

 #define CONFIG_PLUGIN_BINDDN_TRACKING_ATTRIBUTE "nsslapd-plugin-binddn-tracking"

 #define CONFIG_MODDN_ACI_ATTRIBUTE "nsslapd-moddn-aci"

+#define CONFIG_TARGETFILTER_CACHE_ATTRIBUTE "nsslapd-targetfilter-cache"

 #define CONFIG_GLOBAL_BACKEND_LOCK "nsslapd-global-backend-lock"

 #define CONFIG_ENABLE_NUNC_STANS "nsslapd-enable-nunc-stans"

 #define CONFIG_CONFIG_ATTRIBUTE "nsslapd-config"

@@ -2315,6 +2316,7 @@ typedef struct _slapdFrontendConfig

     char **plugin;

     slapi_onoff_t plugin_track;

     slapi_onoff_t moddn_aci;

+    slapi_onoff_t targetfilter_cache;

     struct pw_scheme *pw_storagescheme;

     slapi_onoff_t pwpolicy_local;

     slapi_onoff_t pw_is_global_policy;

-- 

2.31.1